<template>
  <div class="camera_outer">
    <video id="videoCamera" :width="videoWidth" :height="videoHeight" autoplay></video>
    <canvas style="display:none;" id="canvasCamera" :width="videoWidth" :height="videoHeight"></canvas>

    <div v-if="imgSrc" class="img_bg_camera">
      <img :src="imgSrc" alt class="tx_img" />
    </div>
    <button @click="getCompetence()">打开摄像头</button>
    <button @click="stopNavigator()">关闭摄像头</button>
    <button @click="setImage()">拍照</button>
  </div>
</template>
 <script>
export default {
  data() {
    return {
      videoWidth: "100%",
      videoHeight: "100%",
      imgSrc: "",
      thisCancas: null,
      thisContext: null,
      thisVideo: null
    };
  },
  methods: {
    // 调用权限（打开摄像头功能）
    getCompetence() {
      var _this = this;
      this.thisCancas = document.getElementById("canvasCamera");
      this.thisContext = this.thisCancas.getContext("2d");
      this.thisVideo = document.getElementById("videoCamera");
      // 旧版本浏览器可能根本不支持mediaDevices，我们首先设置一个空对象
      if (navigator.mediaDevices === undefined) {
        navigator.mediaDevices = {};
      }
      // 一些浏览器实现了部分mediaDevices，我们不能只分配一个对象
      // 使用getUserMedia，因为它会覆盖现有的属性。
      // 这里，如果缺少getUserMedia属性，就添加它。
      if (navigator.mediaDevices.getUserMedia === undefined) {
        navigator.mediaDevices.getUserMedia = function(constraints) {
          // 首先获取现存的getUserMedia(如果存在)
          var getUserMedia =
            navigator.webkitGetUserMedia ||
            navigator.mozGetUserMedia ||
            navigator.getUserMedia;
          // 有些浏览器不支持，会返回错误信息
          // 保持接口一致
          if (!getUserMedia) {
            return Promise.reject(
              new Error("getUserMedia is not implemented in this browser")
            );
          }
          // 否则，使用Promise将调用包装到旧的navigator.getUserMedia
          return new Promise(function(resolve, reject) {
            getUserMedia.call(navigator, constraints, resolve, reject);
          });
        };
      }
      var constraints = {
        audio: false,
        video: {
          width: this.videoWidth,
          height: this.videoHeight,
          transform: "scaleX(-1)"
        }
      };
      navigator.mediaDevices
        .getUserMedia(constraints)
        .then(function(stream) {
          // 旧的浏览器可能没有srcObject
          if ("srcObject" in _this.thisVideo) {
            _this.thisVideo.srcObject = stream;
          } else {
            // 避免在新的浏览器中使用它，因为它正在被弃用。
            _this.thisVideo.src = window.URL.createObjectURL(stream);
          }
          _this.thisVideo.onloadedmetadata = function(e) {
            _this.thisVideo.play();
          };
        })
        .catch(err => {
          console.log(err);
        });
    },
    //  绘制图片（拍照功能）

    setImage() {
      var _this = this;
      // 点击，canvas画图
      _this.thisContext.drawImage(
        _this.thisVideo,
        0,
        0,
        _this.videoWidth,
        _this.videoHeight
      );
      // 获取图片base64链接
      var image = this.thisCancas.toDataURL("image/png");
      _this.imgSrc = image;
      this.$emit("refreshDataList", this.imgSrc);
    },
    // base64转文件

    dataURLtoFile(dataurl, filename) {
      var arr = dataurl.split(",");
      var mime = arr[0].match(/:(.*?);/)[1];
      var bstr = atob(arr[1]);
      var n = bstr.length;
      var u8arr = new Uint8Array(n);
      while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
      }
      return new File([u8arr], filename, { type: mime });
    },
    // 关闭摄像头

    stopNavigator() {
      this.thisVideo.srcObject.getTracks()[0].stop();
    }
  }
};
</script>
<style lang="scss" scoped>
  .camera_outer{
    position: relative;
    overflow: hidden;
    background: url("~@/assets/imgs/houtai/wutu.png") no-repeat center;
    background-size: 100%;
    video,canvas,.tx_img{
      -moz-transform:scaleX(-1);
      -webkit-transform:scaleX(-1);
      -o-transform:scaleX(-1);
      transform:scaleX(-1);
    }
    .btn_camera{
      position: absolute;
      bottom: 4px;
      left: 0;
      right: 0;
      height: 50px;
      background-color: rgba(0,0,0,0.3);
      line-height: 50px;
      text-align: center;
      color: #ffffff;
    }
    .bg_r_img{
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      top: 0;
    }
    .img_bg_camera{
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      top: 0;
      img{
        width: 100%;
        height: 100%;
      }
      .img_btn_camera{
        position: absolute;
        bottom: 0;
        left: 0;
        right: 0;
        height: 50px;
        line-height: 50px;
        text-align: center;
        background-color: rgba(0,0,0,0.3);
        color: #ffffff;
        .loding_img{
          width: 50px;
          height: 50px;
        }
      }
    }
  }
  </style>
